Method of conditioning forming rollers to form glass ceramic



June 10, 1969 L E 3,449,100

J ---M'ET H0D"OF CONDITIONING FQBMINGERQLLER S TO FORMGLASS 'CERAM III C Filed Nov. 17, 1965 ROLL FORMING A QUANTITY OF GLASS CERAMIC CONTAINING AN EFFECTIVE AMOUNT OF AT LEAST O25 PERCENT BY WEIGHT 'OF FLUORINE.

THEREAFTER ROLL FORMING HIGH DIELECTRIC CONSTANT FLUORINE FREE GLASS CERAMIC WITH THE SAME ROLLERS.

FIG. 2

INVENTOR. Richard E. Allen ATTORNEY United States Patent i f gg a free fluorine basis is first rolled by rollers 10 and 12. 3,449,100 Such rolling conditions the surface of the rollers to reduce METHOD OF CONDITIONING FORMING ROLLERS the adhesion thereto of substantially fluorine free high TO FORM QLASS CERAMIC dielectric constant glass ceramic. A material suitable for Rlchal'd Allen, Comlngs -r asslgnol' to Commg conditioning the rollers is as follows in percent by weight:

Glass Works, Corning, N.Y., a corporation of New 5 10.5 percent BaO, 8.5 percent SrO, 180 percent Pbo,

York Filed Nov. 17 196's sen 508,266 48.0 percent Nb O 7.5 percent SiO 3.0 percent A1 Int. 1 C03!) 13/02 39/00 2.5 percent B203, and 2.0 percent BaF CL 65 24 5 Claims In refining Nb O fluorine may be used, and in such manufacture a fluorine residue remains. The amount of such a residue may be easily controlled. It has been found that if Nb O containing such a fluorine residue is used ABSTRACT OF THE DISCLOSURE in the glass ceramic batch materials, the resulting ma- A method of conditioning glass forming rollers to terial may be used to condition the rollers for subsequent duce adhesion thereto of molten high di l t i constant 1 fluorine free materials, if the fluorine residue comprises an fluorine free glass ceramic and glass compositions by first efiecilve l of at least Pe cent by we1ght of rolling a quantity of molten glass ceramic or glass maq A le xample of a glas ceram c t al terial containing an effective amount of at least 0.25 per- Yvhlch Was Prepared h h a fluo ine residue containcent Weight of fluorine computed on a free fluorine mg Nb O 1s as follows 1n welght percent exclusive of the b (1, th r after, rollin said fluorine free com osition fluorine: 12.5 percent BaO, 8.5 percent SrO, 17.5 percent i g g 1: g p PbO, 48.5 percent Nb O 7.5 percent SiO and 2.9 percent Al O 2.5 percent B 0 and 0.1 percent Fe O Other examples of compositions in weight percent, t

g which fluorine in effective amounts of at least 0.25 per- F the p p of thls lnventlon the term glass cent by weight may be added, effective for conditioning ramic is intended to include glass which can be ceramed glass forming rollers, is shown in Table L after roll forming by proper treatment as well as other glass. A high dielectric constant as used herein is defined TABLE I as at least 25. Halo 11.5-14.1 In the roll forming of a thin glass ceramic ribbon s SrO 7.9-9.6 as is suitable for use as a dielectric in a stacked c p r PbO 16.o 19.7 it has been found that the fluorine free glass ceramlc Nb O 43.5-53.5 ribbon sticks to the rollers, is caused to whip around t SiO 7.0-8.0 rollers, completely wraps around the s, beeomes A1 0 2.5-3.5 checked, and breaks up into small pieces. Only very sm B 0 2.0-3.0 amounts of ri n Could be made and that y under After the rollers are conditioned, high dielectric contransient COHditiOIlS- Such ProblemS are magnified y the stant, fluorine free glass ceramic, such as that shown in fact that s ribbon is y Small and thin, as for Table II in weight percent, can thereafter be roll formed ample 0.0016 inch thick and 0.225 inch wide. i a ibb It is an object of the present invention to provide a TABLE II economical method of producing significant quantities of thin glass ceramic ribbon.

Another object of this invention is to reduce the adhesion of molten glass ceramic ribbon to the surfaces of forming rollers.

Broadly, according to the present invention a method of conditioning glass forming rollers to reduce adhesion thereto of substantially fluorine free high dielectric constant glass ceramic material by roll forming with said rollers a quantity of glass ceramic containing an eifective Examples 1 amount of at least 0.25 percent by weight of fluorine InExample 2, the totalof SiOz, A1203, and BtOsbeingbetween 11 and computed on a free fluorine basis, etfectlve to condit on 14 Dwellt by welghtsaid rollers, before rolling the fluorine free material. A typical example of the present i ti i as fol.

Additional objects, features and advantages of the preslows. A batch of material was prepared containing by ent invention will become apparent to those skilled in th weight 10.5 percent BaO, 8.5 percent SrO, 18.0 percent art, from the following detailed description and the at- P bO, 48.0 percent Nb O 7.5 percent SiO 3.0 percent tached drawing on which, by way of example, only the A1 0 2.5 percent B 0 and 2.0 percent BaF The batch preferred embodiment of this invention is illustrated. was melted in a crucible and formed approximately 700 FIGURE 1 is an elevation view of ribbon roll formed grams of molten material. It was then roll formed by a in accordance with the present inventionpair of A1 0 clad steel rollers to suitably condition the FIFGURE 2 is a flow diagram illustrating the method lle of the present invention. Thereafter a batch of high dielectric constant, fluorine Referring to FIGURE 1, there is shown a pair of glass free glass ceramic having a viscosity of 0.5 poise and a forming rollers 10 and 12. Rollers 10 and 12 have a liquidus of 1200 C. was melted in a crucible and roll coating 14 of A1 0 on the rolling surfaces. A S r am 1 formed into a uniform ribbon having a thickness of about of molten glass ceramic is emitted from a suitable nozzle 0.0016 inch and a Width of about 0.225 inch. The glass 18 to the bite between the rollers. Ribbon 20 is formed eramic was composed by weight of 13.0 percent BaO, by the rollers which rotate in the direction of the arrows 9,0 percent S O, 18,0 percent 1 b0, 4&0- percent Nb o shown. 7.5 percent SiO 2.0 percent A1 0 and 2.5 percent B 0 n accordance With the P I F lnventloll a q y of 7 Before conditioning, the fluorine free glass ceramic molten glass ceramic contalnl-ng an efiectlve amount of readily adhered to the roller surfaces, whipped about and at least 0.25 percent by Weight of fluorine computed on wrapped around the rollers in addition to checking and breaking into small pieces. After the rollers were conditioned about 1000 grams of excellent quality thin ribbon was produced before the conditioning wore off.

The compositions illustrated in Table II, Example 2 are suitable for manufacture of fluorine free ribbon for capacitor dielectric purposes.

Although the present invention has been described with respect to specific details of certain embodiments thereof, it is not intended that such details be limitations upon the scope of the invention except insofar as set forth in the following claims.

I claim:

1. In the process of rolling a high dielectric constant substantially fluorine-free glass ceramic comprising the steps of providing forming rollers having a cladding of A1 on the rolling surfaces thereof, and

rolling a molten stream of said fluorine-free ceramic by said clad rollers, the improvement of conditioning said rollers to reduce the adhesion of said fluorine-free glass ceramic thereto comprising the step of rolling by said clad rollers a quantity of molten glass ceramic containing an effective amount of at least 0.25% by weight of fluorine computed on a freefluorine basis for a period of time sufficient to reduce the adhesion thereto of said fluorine-free glass ceramic prior to said step of rolling thereof.

2. In the process of claim 1 fluorine containing glass ceramic consisting essentially by weight of 10.5% BaO, 8.5% SrO, 18.0% PbO, 48.0% Nb O 7.5% SiO 3.0% A1203, B203, and BaF2.

3. In the process of claim 1 fluorine containing glass ceramic consisting essentially by weight of between 11.5 to 14.1% BaO, 7.9 to 9.6% SrO, 16.0 to 19.7% PbO, 43.5 to 53.5% Nb O 7.0 to 8.0% SiO 2.5 to 3.5% Al O and 2.0 to 3.0% B 0 to which has been added at least 0.25% by weight of fluorine, computed on a freefluorine basis.

4. In the process of claim 3 fluorine-free glass ceramic consisting essentially by weight of between 11.5 to 14.1% BaO, 7.9 to 9.6% SrO, 16.0 to 19.7% PbO, 43.5 to 53.5% Nb O 6.0 to 9.0% SiOg, 1.0 to 3.0% A1 0 and 1.5 to B203, the total of SigO, A1203, and B203 being between 11 and 14%.

5. A process for rolling a thin ribbon of high dielectric constant substantially fluorine-free glass ceramic comprising the steps of providing glass rolling means having a cladding of A1 0 on the rolling surfaces thereof,

rolling by said clad rolling means a quantity of molten glass ceramic containing an effective amount of at least 0.25% by weight of fluorine computed on a free-fluorine basis for a period of time sufficient to reduce the adhesion to said surfaces of said fluorinefree glass ceramic, and thereafter rolling by said clad rolling means said fluorine-free glass ceramic in molten form, whereby said ribbon is formed without sticking to said clad surfaces.

References Cited UNITED STATES PATENTS 1,422,036 7/ 1922 Crowley et al. 26 2,470,461 5/1949 Black 6524 XR 2,697,676 12/1954 Black et al. 6524 XR 3,208,839 9/1965 Nordberg 6524 3,218,140 11/1965 Francel et al. 6526 XR 3,325,265 6/1967 Stookey 6533 XR 3,341,315 9/1967 Patschorke 6526 XR 3,347,650 10/1967 Barkhan 6526 S. LEONE BASHORE, Primary Examiner.

FRANK W. MIGA, Assistant Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,449,100 June 10, 1969 Richard E. Allen It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 61, "FIFGURE" should read FIGURE Column 4 line 5, "Si O" should read Si0 Signed and sealed this 14th day of April 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

